Concrete finishing device



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Patented Dec. 22, 1942 UNITED STATES PATENT OFFICE CONCRETE FINlSHING DEVICE Gordon M. Tamblyn, Denver, Colo.

Application August 9, 1941, Serial No. 406,082

9 Claims.

This invention relates to a concrete surfacing device and has for its principal object the provision of a highly eiiicient device of this character which can be passed over a freshly poured concrete surface such as a roadway, floor, platform, or sidewalk and which will vibrate, agitate, and pack the concrete to a rough level and which will then finish off this roughly leveled surface to a perfect finished surface; and which will quickly accomplish the above over an exceedingly wide area with very little man power.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efliciency. These will become more apparent from the following description.

In the following detailed description of the invention reference is had to the accompanying drawings which form a part hereof. Like numerals refer to like parts in all views of the drawings and throughout the description.

In the drawings:

Fig. 1 is a plan view of the improved concrete surface finishing device;

Fig. 2 is a side View thereof;

Fig. 3 is an enlarged cross section, taken on the line 3-3, Fig. 1; and

Fig. 4 is a detail section taken on the line 4-4, Fig. 2.

The invention is designed to be supported upon any suitable runways I0 which are elevated above the surface of the concrete which is indicated at II upon suitable screed legs I2. Such a runway is described in applicants co-pending application Serial No. 398,381.

The improved concrete finishing device employs two parallel, longitudinally-extendingy supporting members I3 preferably, but not necessarily, formed of pipe or tubing. The supporting members I3 extend from one runway IIJ to the other and rest thereon. They terminate at both extremities in upwardly extending handle members I4. The supporting members I3 carry a frame member I5 provided with outwardly extending arms having upwardly-recessed extremities |5 which rest on the members I3.

Clamping plates II actuated by clamp bolts I3 are employed to clamp the members $3 in the extremities I6. two spaced-apart, vertical bearing sleeves i9 carrying ball thrust bearings 20. A shaft sleeve 2| is mounted in each of the bearings 20 so as to freely rotate therein. This shaft sleeve surrounds a vertical threaded shaft 22. The shafts e The frame member I5 carries J.

22 extend at their upper extremities through bevel gears 23.

When in operation, the gears are locked on the shafts 22, and the shafts are locked in the shaft sleeves 2|, by means of suitable locking keys 24. The gears 23 mesh with bevel pinions 25 on the extremities of a power shaft 25. The power shaft 26 is journalled in pedestal bearings 2l on the frame member I5.

The shaft 26 is driven from a suitable motor 28 through the medium of a sprocket chain 29 and sprocket gears 30. A crank arm 3| is secured on the lower extremity of each shaft 22. These crank arms extend outwardly to the same side of both shafts 22 to support a longitudinally extending trowel bar 32. The trowel bar is suspended from the arms 3| on suitable bolts 33 and is constantly urged downwardly from these arms by means of compression springs 34. The lower face of the trowel bar is provided with a convex troweling plate 35 which contacts the concrete It can be readily seen that as the motor 28 operates the crank members 3|, they will swing the trowel bar 32 with a circular motion in a horizontal plane so that the soft concrete will be quickly and uniformly brought to a level, 1inished surface throughout the entire length of the device.

To obtain the greatest efficiency from concrete it is desirable to tamp .it into place prior to troweling. This is accomplished by means of a plurality of parallel, vertically-extending, tamping bars 36 which are mounted in suitable yokes 31 on the lower extremities of connecting rods 38. The tamping bars are secured in the yokes by means of attachment bolts 39 which pass through all of the bars. The bars are separated from each other on the bolts by means of suitf' able separators 40,

The connecting rods 38 extend upwardly to cranks 4|, there being one crank on each extremity of a crank shaft 42 which is mounted in bearing blocks 43 on the frame member I5. The crank shaft 42 is driven from the power shaft 26 by means of a drive chain 44 extending from a free sprocket 45 on the shaft 26 to a fixed sprocket 46 on the shaft 42. The sprocket 45 is provided with clutch teeth which engage similar teeth on a clutch member 4l. The clutch member 41 is slidably secured on the shaft 2S so that, when it is brought into engagement with the teeth on the sprocket gear 45, the latter will rotate with the shaft 26. The rotation of the shaft 42 through the medium of the cranks 4| reciprocates the tamping bars 36 with a vertical jiggling or tamping motion.

Operation The screed legs I2 are erected over the surface which is to bear the concrete. The runways I0 are secured in the screed legs and brought to a perfect horizontal plane throughout their lengths and with each other. The concrete is poured and brought to a rough finish by means of any suitable screed, resting on and guided by the runways I0. This screed may have a construction as illustrated and described in applicants said co-pending application.

After the concrete surface has been roughed into place, this improved device is placed on the runways and the motor started. It is then pushed back and forth and along the runways by means of an operator at each pair of the handle members I4. This causes the tamping bars to proceed the trowel member so that their vertical vibrating motion will tamp the concrete into place. The tamping bars are then followed by the trowel bar 32 which is swinging in a circular motion so as to trowel down the surface of the concrete to a perfect level determined by the accuracy of the pre-set level of the runways I0.

By adding moisture to the concrete surface beneath the trowel plate 35, this surface can be brought to a perfect smooth nish without the use of hand labor. This surface will be perfectly fiat, level, and horizontal. Should the trowel bar strike hardened concrete or other incompressible obstruction it will rise upwardly thereover compressing the springs 34.

Before starting the device, the trowel bar 32 is raised or lowered and leveled so that its final position will be on the desired finish plane of the concrete. This adjustment is made by removing the locking keys 24 and rotating the gears 23 to thread the shafts 22 upwardly or downwardly. When the desired position has been reached, the locking keys 24 are again inserted.

While a specific form of the improvement has been described and illustrated herein, it is desired to be understood that the same may be varied, within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by Letters Patent is:

l. A concrete finishing device comprising: a frame member; a pair of Vertical shafts extending downwardly from said frame member; a crank extending outwardly from each shaft: an elongated trowel bar pivotally suspended from both said cranks so that the rotation of the latter will swing the former in a circular path; and means for simultaneously rotating said shafts.

2. A concrete finishing device comprising: a frame member; a pair of spaced apart vertical shafts extending downwardly from said frame member; a crank extending outwardly from each shaft in parallel relation to each other; an elongated trowel bar pivotally connected to each of sai-:l cranks so that the rotation of the latter will swing the former in a circular path; and means for rotating said shafts in unison.

3. A concrete finishing device comprising: a frame member; a pair of vertical shafts extending downwardly from said frame member; a crank extending outwardly from each shaft; an elongated trowel bar pivotally suspended from said cranks so that the rotation of the latter will swing the former in a circular path Without end to end rotation; means for rotating said shafts; and means for simultaneously adjusting both of said shafts upwardly and downwardly to change the elevation of said trowel bar while maintaining it parallel to said surface.

4. A concrete finishing device comprising: a frame member; means for movably supporting said frame member over the concrete surface; a horizontal elongated trowel bar positioned below said frame member; means for supporting and swinging said trowel bar with a circular movement in a plane parallel to said surface with the longitudinal axis thereof at any position being parallel to its axis at any other position, said means consisting of a pair of spaced-apart cranks supported by said frame member so as to rotate in the same horizontal plane, said cranks being positioned parallel to each other; means for suspending said trowel bar from said cranks; and means for rotating said cranks in unison so that they will maintain their parallel relation.

5. A concrete finishing device comprising: a frame member; a pair of spaced-apart, vertical shafts extending downwardly from said frame member; a crank extending outwardly from each shaft in parallel relation; an elongated trowel bar pivotally connected to each of said cranks so that simuitaneous rotation of the latter will swing the former in a circular path, the effective lengths of said cranks being equal so that all positions of said trowel bar will maintain a parallel relation; and means for rotating said shafts in unison.

6. A concrete finishing device comprising: a frame member; means for supporting said frame member over a concrete surface to be finished; a pair of spaced-apart vertical shafts rotatably mounted in said frame member and extending downwardly therefrom toward said surface; means for rotating said shafts in unison; a crank member extending horizontally outward from each of said shafts in substantially parallel relation; a horizontal, elongated trowel bar extending across both crank members below the latter; and a pivotal connection between each crank member and said trowel bar so that simultaneous rotation of the former will reciprocate said bar in a circular path in a horizontal plane over said surface.

'7. A concrete finishing device comprising: a frame member; means for supporting said frame member over a concrete surface to be finished; a pair of spaced-apart vertical shafts rotatably mounted in said frame member and extending downwardly therefrom toward said surface; means for rotating said shafts in unison; a crank member extending horizontally outward from each of said shafts in substantially parallel relation; a horizontal, elongated trowel bar extending across both crank members below the latter; and a pivot member extending upwardly from said trowel bar through each of said crank members eccentric to the axis of the latter so that simultaneous rotation of said crank members will im.- part a circuiar reciprocation to said trowel bar.

8. A concrete finishing device comprising: a frame member; means for supporting said frame member over a concrete surface to be finished; a pair of spaced-apart vertical shafts rotatably mounted in said frame member and extending downwardly therefrom toward said surface; means for rotating said shafts in unison; a crank member extending horizontally outward from each of said shafts in substantially parallel relation; a horizontal, elongated trowel bar extending across both crank members below the latter; a pivot member extending upwardly from said trowel bar through each of said crank members eccentric to the axis of the latter so that simultaneous rotation of said crank members will impart a circular reciprocation to said trowel bar; and springs urging said trowel bar downward from said crank members.

9. A concrete finishing device comprising: a frame member; means for supporting said frame member over a concrete surface to be finished; a pair of spaced-apart Vertical shafts rotatably mounted in said frame member and extending downwardly therefrom toward said surface; a

crank member extending horizontally outward from each of said shafts in substantially parallel relation; a horizontal, elongated trowel bar extending across both crank members below the latter; a pivotal connection between each crank member and said trowel bar so that simultaneous rotation of the former will reciprocate said bar in a circular path in a horizontal plane over said surface; threads formed on each of said shafts; a driving wheel threaded on the threads of each shaft; means for rotating said driving wheels in unison to cause the coacting threads to move said shafts axially; and means for locking said wheels to said shafts when desired to cause the latter to rotate with the former.

GORDON M. TAMBLYN. 

